Systematical　research　was　implemented　to　explore　the　impacts　of　fiber　reinforcement　index　VfLf/d(f)　(i.e.,　the　product　of　fiber　volume　V-f　and　fiber　aspect　ratio　L-f/d(f))　on　the　energy　dissipation　characteristics　including　strain　energy　density　and　fracture　energy,　of　polyethylene　fiber-reinforced　engineered　cementitious　composites　(PE-ECC)　with　compressive　strength　varying　from　normal　to　high.　Six　VfLf/d(f)　values　(i.e.,　5,　7.5,　9,　10,　15,　and　18)　and　five　water/binder　ratios　(i.e.,　0.14,　0.16,　0.18,　0.22,　and　0.32)　were　considered　in　total.　Strain　energy　density　and　fracture　energy　reflect　the　crack　resistance　capacity　during　the　strain-hardening　and　softening　processes　of　PE-ECC,　respectively.　The　strain　energy　density　of　PE-ECC　increased　significantly　with　the　increase　of　VfLf/d(f)　and　the　decrease　of　water/binder　ratio.　The　fracture　energy　increased　noticeably　with　the　growth　of　VfLf/d(f),　while　it　attained　the　maximum　value　at　the　water/binder　ratio　of　0.16.　For　ECC　including　both　the　strain-hardening　and　softening　processes,　neither　the　strain　energy　density　nor　fracture　energy　alone　can　reflect　its　crack　resistance　capacity　and　energy　dissipation　capacity　comprehensively.　Thus,　in　the　design　and　simulation　processes　of　ECC,　both　energy　parameters　need　to　be　considered　in　the　constitutive　model.